Deciding How Far Apart to Plant Large Trees

pamchesbayMay 4, 2007

Hello:

After a day at a botanical garden, I have questions about how far apart to plant large trees - bald cypresses, dawn redwoods, deodara cedars, oaks, maples, tulip polars.

The tags usually say to plant these trees at least 25 feet apart, often 50 feet apart. Since the trees I'm planting are small (i.e., white oak: 2.5-3 ft; maples: 6-8 ft; tulip tree: 4-5 feet; bald cypresses: 5 to 8 feet), these trees are nearly lost in the 4-5 acre field between the house and road. (I tied lightweight orange ribbon around the small ones so I wouldn't accidently cut them down when mowing the field)

Last week, I went to the Ginter Botanical Gardens in Richmond with a camera and notebook. The first thing I noticed was a group of tall deodara cedars planted on a berm - 10-12 ft apart. A group of 4 dawn redwoods was 6 feet apart.

At the entrance to the main building are two groves of dawn redwoods - 9-12 feet apart.

In addition to taking notes and photos, I ended up measuring distances between trees. In every single case, trees were planted much closer than than recommended.

* Bald and pond cypresses: 6-8 ft apart, sometimes a little less or more

I finally stopped measuring because the trees were always planted closer than recommended.

Question: How do you make decisions about spacing trees?

I'm planting lots of small trees that will grow into large trees- eventually. I like the fact that I can plant trees much closer together than recommended on the nursery tags. But how do you know what is "too close"?

I take spacing more seriously with regards to distance from buildings than other trees. Most of the time I want the canopies to overlap some so I'd plant a little less than half the anticipated mature size for something like a street planting. The closer you plant the more narrow growing they will be, just like in a forest but that may not be the ideal size for your situation. If you want to reforest, plant closer. If you want big trees to spread out like in a park and reach their maximum potential size then plant farther apart.

So for some landscapes or some kind of exhibit I would understand those planting distances but like I said it depends on what you want.

otherwise ... trees planted too close together ... will kill the weak ones... they will take care of it all for you ....

when planting .... mow the area ... and use credit/roundup to kill a 3 foot circle .... a week later.. plant the tree in the middle ... mulch the 3 foot area.. or continue the credit for a couple years ..... weed/competition reduction is probably more important than anything ... this avoids the need to worry about mowing... if you miss a 3 foot circle ....

It depends on if you want specimen trees or a grove. For specimens, plant as far apart as possible, to allow for full, unobstructed growth on all sides. If you want the crowns to overlap and grow into each other, then plant at a distance that will allow that. Just try to allow enough room that a faster growing tree won't out-grow and shade out/kill a slower one. As Ken said, a taller, stronger tree will probably eventually kill off a smaller tree - understory trees, such as dogwood, etc., might be able to adapt to the increasing shade, as they can to more sun, but will be less strong, due to less light, and will probably lose branches.

Do you want grass under and around the trees eventually, or are you looking to recreate the forest that probably existed however many years sgo, before the field was cleared? If you want to keep the grass, then you need wider spacings than if "forest" is your intent.

Don't forget also, public gardens need to make an impact NOW, so they may be planning to remove the weaker one(s) of a group of trees after a few years, thinning out a planting that is really too close together, but which would now be "blah" at the correct spacing for ideal growth.

As far as spotting newly planted trees in long grass - I go to a neighbor's well-established (and escaping) bamboo grove (with permission) and cut canes most summers. I cut these into 6-7' lengths - so I can reach the tops with a hammer, standing on an upturned 5-gal. bucket - and pound them in next to each newly planted tree. The top is usually visible above the grass. If not, tieing surveyors tape to it will increase the visibilty. I do go around and make sure they stay standing at least once in a summer. It's easier to pound them in after a good rain, or next to the root ball right after planting and watering. This way, also, if you are out watering, you are less likely to skip one accidentally.

Do you use roundup to keep down vegetation around trees AFTER planting? Don't you risk killing the trees by using it?

If roundup is safe to use around trees, my life is about to become much easier! Let me ask you another question.

A few weeks ago, Spruce talked about planting bald cypresses close together so a person could lie down and see the spires against the sky. This led me to plant 3 bald cypresses 12-15 feet apart in an open area close to the Bay (spires, sky and water). I used roundup in advance so each tree is in it's own little circle, with a moat and mulch.

After I finished, I decided the area needed at least one more bald cypress. I also decided that the area around the trees should be relatively free of grass, except for a grass path through the grove that continues to a newly planted stand of beach plums and native switch grass.

But - to implement this plan, I would have to dig up a large area of thick grass - very labor intensive and time-consuming. I have the 4th bald cypress, but haven't planted it yet.

Your post caused me to wonder if there is an alternative to digging up the grass. If I use roundup to clear the grass between the bald cypresses, and some roundup drifts onto the trees, this won't kill them?

You should be safe with the roundup.
I use it around trees although I try not to. It makes me nervous but not really for any good reason. If the grassy weeds to too tough to pull out, I spray them with roundup.

Your answers caused me to have more questions. The program won't let me post another question unless I change the subject so I'm putting these questions into a single post.

quirkyquercus: Thanks for clarifying the difference in spacing for specimen trees v. trees to form a canopy. In most places, I do want overlapping canopies. Your answer led me to have another question,

You wrote, "If I want the canopies to overlap, I'd plant a little less than half the anticipated mature size..."

Q: If the mature width is 50 feet, you might plant approximately 20 feet apart, give or take a little? Is my understanding correct?

If so, I want to move a few trees planted within the past week or two - IF another move won't hurt them (they are Autumn Blaze maples).

dibbit:

Grass is not important. At the cottage where I used to live, I had grass paths between beds. The less grass, the less time spent mowing.

I'd like to reforest the property using different trees and plantings, depending on the characteristics of an area. The property has several areas that are very different - a sand beach and dunes; a big open field; a protected area that overlooks a cove; a shallow pond that we are laboring to clean out and make healthier. The 'pond' is actually a ditch abandoned by VDOT for decades, the culvert got clogged up, a narrow ditch became a wide, shallow mosquito filled swale or 'pond' into which the summer people threw their trash and old appliances.

Some areas are hard to access because they are so overgrown. These areas are wildlife heavena so I probably won't do much except make a path, try to keep the invasive stuff under control.

I understand that public gardens may do things for short-term impact. What struck me here was that this garden used groves of dawn redwoods at the entrance to their main building. They can't cut these trees down in a few years because they planted them too close. I concluded that they didn't plant the redwoods too close, that the redwoods are okay being planted this close.

We Virginians love our trees. If a botanical garden destroyed healthy trees because they didn't plan properly, they would be committing organizational suicide.

I am using surveyer's tape as a reminder about newly planted trees that will need to be watered more often. Thanks for the tip about bamboo stakes and the 5 gallon bucket. I can do that - it's an improvement over my technique.